DNA barcoding and cryptic new species discovery of Chimonocalamus
(Poaceae: Bambusoideae)
Abstract
Chimonocalamus is a medium sized genus with distinguished morphological
characteristics at the generic level. However, species identification in
this genus can be confused due to similar morphological features and
overlapped geographical distribution. To clarify the delimitation and
confirm the identities of Chimonocalamus species in China, plastomes and
nrDNAs of 49 accessions of 10 known species and three putative new
species were newly retrieved by genome skimming. Distance-based and
tree-based methods were conducted to analyze the species discrimination
rate of five datasets. Meanwhile, Skmer method was also exploited. The
results indicated that Skmer analyses had the highest discriminatory
power with nine species identified (69.23%). The plastomes showed much
higher discriminatory success rate than the combination of three
standard plastid DNA barcodes which performed worst among the five
datasets. According to the tree-based analysis, the C. fimbriatus
complex was designated. This complex bears few morphological differences
and the species delimitation needs to be further studied at the
population level. Nevertheless, the three potentially new species of
Chimonocalamus were confirmed by the plastome and nrDNA datasets, and
Skmer analysis, together with morphological difference. Herein, we
described and illustrated them as new to science, i.e., C. hekouensis Y.
X. Zhang, Gui L. Zhang & D.Z. Li, C. hsuehiorum D.Z. Li & Y.X. Zhang,
and C. shuangjiangensis D.Z. Li & Y.X. Zhang. Taken together, plastomes
and nrDNAs could serve as effective super-barcodes for species
discrimination of Chimonocalamus, playing important roles in recognition
of cryptic new species, and Skmer analysis can be adopted in molecular
identification.